Articles, Business

FIFO, LIFO, and SIRO: Understanding the Pros and Cons of Each Type of Queueing System

Queuing Illustration. Source: Freepik.

In today’s fast-paced business environment, managing queues efficiently is crucial for providing excellent customer service, reducing wait times, and increasing productivity. The key is to implement the most suitable queueing system.

A queueing system is a method of organising and processing customers, tasks, or requests in a specific order. There are three primary types of queueing systems: First-In-First-Out (FIFO), Last-In-First-Out (LIFO), and Service-In-Random-Order (SIRO). Each system has its strengths and weaknesses. Therefore, it is essential to choose the right one for your business.

FIFO (First-In-First-Out)

FIFO Queuing Illustration. Source: Freepik.

FIFO is the most commonly used queueing system, where customers are served in the order they arrive. This system is simple and easy to implement, making it a popular choice for businesses that prioritise fairness and first-come-first-served policies.


  • Fairness: Customers are served in the order they arrive. It promotes transparency and prevents frustration.
  • Simplicity: It is easy to implement and manage, with minimal administrative tasks required.
  • Predictability: Customers can estimate their waiting time based on the queue length, allowing for better planning.


  • Potential for longer waiting times: Customers who arrive later may have to wait significantly longer, especially during peak hours.
  • Limited flexibility: FIFO does not prioritise urgency or importance, which potentially leads to bottlenecks and inefficiencies.

Best suited for:

  • Retail stores
  • Banks
  • Restaurants
  • Any business that prioritises fairness and orderliness

LIFO (Last-In-First-Out)

LIFO Queuing Illustration. Source: Freepik.

LIFO, on the other hand, is a type of queueing system where the last customer in line is served first. This system is often used in businesses that require priority service for certain customers, such as VIPs or those with urgent needs.


  • Speed: It can help reduce wait times for customers who have urgent needs or are short on time.
  • Urgency: LIFO allows for priority service for certain customers, ensuring that their needs are met quickly and efficiently.
  • Efficiency: Can be effective in fast-paced environments where rapid response is crucial.


  • Unfairness: Customers who have been waiting longer may feel frustrated and dissatisfied.
  • Limited predictability: Waiting times become unpredictable, making it difficult for customers to plan.
  • Extra workload for staff: LIFO requires more administrative tasks, such as identifying VIPs or prioritising customers based on their needs.

Best suited for:

  • Emergency rooms
  • Hotels
  • Any business that prioritises urgency and VIPs

SIRO (Service-In-Random-Order)

SIRO Queuing Illustration. Source: Freepik.

SIRO is a type of queueing system where customers are served in a random order, rather than the traditional first-in-first-out or last-in-first-out methods. This system is often used in businesses that require a more efficient way to manage customer flow and minimise wait times.


  • Reduced perceived waiting time: Studies show that random queueing feels faster than structured queues, leading to higher customer satisfaction.
  • Increased fairness: Everyone has an equal chance of being served next, which eliminates the feeling of unfairness.
  • Improved efficiency: SIRO can optimise resource allocation by assigning the most suitable staff to serve customers and their specific needs.


  • Unpredictability: Customers cannot estimate their waiting time, potentially leading to frustration and anxiety.
  • Complexity: Implementing and managing a random queueing system can be challenging.
  • Potential for customer confusion: The lack of a clear order can lead to confusion and frustration, especially for first-timers.

Best suited for:

  • Amusement parks
  • Call centres
  • Any business that requires a more efficient way to manage customer flow and reduce perceived waiting times

Which Type of Queueing System Suits Your Business?

When deciding which type of queueing system is best for your business, it is important to consider these three factors:

  • The nature of your business operations
  • The importance of fairness and predictability
  • The variation in processing times
Queue Management System Illustration. Source: Freepik.

Simplifying Queue Management with SMARTQUEUE®

Whichever type of queueing system your business utilises, SMARTQUEUE® can make it easier for you. This omnichannel queue management system from Business Smart Solutions (BSS) prioritises customer care and continuous business growth. It supports multiple beneficial modules, such as Virtual Queue, Ticketing Kiosk, Concierge Service, Virtual Caller, Real-Time Dashboard Monitoring, and Reporting Tool. SMARTQUEUE® also offers additional modules, including SMS Notifications and Customer Feedback Solution.

To know more about SMARTQUEUE® and how it can help your business, click here or contact us at for further enquiries.

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